The long range-purpose of this project is to study the biochemical processes involved in the growth of bacterial cell wall and membrane. Of particular interest is the biosynthesis of cell wall teichoic acids and mesosomal lipoteichoic acids in Staphylococcus aureus. The topics of present interest are 1) the theory that lipoteichoic acid occurs in the mesosome of Gram-positive bacteria: 2) the relationship of the high content of lipoteichoic acid in mesosomes to the synthesis of teichoic acid in the cell wall; 3) improvement in methods to isolate mesosomes; 4) the specificity of antibodies in endocarditis patients toward lipoteichoic acid and teichoic acid.